1. Field of the Invention
The invention relates to a valve device.
2. Description of Related Art
Conventionally, in a gas tank provided in a fuel cell vehicle or the like, a valve device is provided to control the supply of high-pressure hydrogen gas into the tank, and the discharge of the high-pressure hydrogen gas stored inside the tank. The valve device includes a body in which a gas flow passage is provided, the gas flow passage providing communication between the inside and the outside of the gas tank; and a valve mechanism that controls the flow of the hydrogen gas through the gas flow passage. The gas flow passage is connected to a pipe extending from an external device (for example a supply source that supplies the hydrogen gas) via a joint fitted to the body (for example, refer to Japanese Patent Application Publication No. 2013-29161 (JP 2013-29161A).
More specifically, as shown in FIG. 7, in a valve device described in JP 2013-29161A, a body 121 has an fitting hole 123 into which a joint 122 is fitted. The body 121 also has a supply passage 124 that is opened to the bottom surface of the fitting hole 123, and that serves as a gas flow passage through which hydrogen gas is supplied into a gas tank. The joint 122 is connected to a pipe 125 such that the pipe 125 is connected to the supply passage 124.
The supply passage 124 is provided with a check valve 132 that suppresses the discharge of the hydrogen gas to the outside through the fitting hole 123. The supply passage 124 includes an increased diameter portion 133 and a valve accommodation portion 134 that are provided in the fitting hole 123-side end portion of the supply passage 124. The increased diameter portion 133 is opened to the bottom surface of the fitting hole 123, and the valve accommodation portion 134 is adjacent to the increased diameter portion 133. The inside diameter of the valve accommodation portion 134 is smaller than the inside diameter of the increased diameter portion 133, and is larger than the inside diameter of the other portion of the supply passage 124. The check valve 132 includes a valve seat 136 in which a valve orifice 135 is provided at a center portion, a poppet 137 that makes contact with and separates from the valve seat 136 so as to close and open the valve orifice 135 (the supply passage 124), and an urging member 138 that urges the poppet 137 toward the valve seat 136.
When the hydrogen gas is not supplied to the gas tank, the poppet 137 is in close contact with the valve seat 136 and is constantly in a closed position due to the pressure of the hydrogen gas and the spring load of the urging member 138, and thus, the poppet 137 suppresses the discharge of the hydrogen gas through the supply passage 124.
When the hydrogen gas is supplied to the gas tank, the poppet 137 is pushed by the load caused by the hydrogen gas, and thus, the check valve 132 is opened. The hydrogen gas is supplied with the use of a pressure difference between the supply pressure and the tank inner pressure. When the pressure difference decreases, the gas flow rate decreases.
When the gas flow rate decreases, the load that pushes the poppet decreases, and as a result, balance between the load and the restoring force of the urging member may be lost. If the balance is lost, the poppet is subject to the fluctuation of the gas flow (that is, the poppet is likely to be influenced by the fluctuation of the gas flow), and as a result, chattering may be caused and thus noise may be caused.